The present inventions relate generally to electric motors, and, more particularly, to motors of the type wherein the energization of motor windings are controlled by switch mechanisms carried on the motor which are actuated by axially movable switch actuating members; to motors of the type that are to be exposed to moisture such as, for example, moisture conditions such as are encountered in outdoor environments; to motors having what are known in the art as outboard switch or accessory device compartments; and to motors wherein it is desirable to provide a motor carried, externally accessible, switch for determining the operational mode or condition of such motor.
As will be understood by persons of ordinary skill in the art, single phase induction motors may be of many different types. Thus, there are resistance start, reactor start, capacitor start, permanent split capacitor, and capacitor start-capacitor run motors to name but a few. These different types of motors are characterized by different speed-torque characteristics, and of course are capable of being designed to have different theoretical maximum efficiencies. For many applications, and especially those where high starting torque is required, it is necessary for part of the windings in the motor to be designed and arranged to be an auxiliary or starting winding which is energized during initial excitation of the motor but which is de-energized as the motor comes up to a predetermined speed.
One particular reference work that describes motor characteristics and gives specific application information regarding different motors is the C. G. Veinott book entitled, "Fractional And Subfractional Horsepower Electric Motors", published by the McGraw-Hill Book Company. For more information on this subject, the reader is directed, for example, to the third edition of the Veinott book which was copyrighted in 1970 by McGraw-Hill.
In many applications, it is known to use a centrifugally or otherwise actuated switch assembly for de-energizing the auxiliary or starting winding as the motor comes up to speed, and it is desirable to optimize such assemblies in terms of material content, assembly cost, and reliability. Some problems with some switch assembly designs that have been used heretofore, are believed to have been associated with a condition wherein the switch contacts have been "open" to their environment and subject to damage, or to lodging of foreign material on or about such contacts. Another continuing concern for all types of motor circuit controlling switches is the question of accessibility or serviceability of such switches as well as the cost associated with replacing such switches. It thus also would be desirable to provide a new and improved switch of non-complex design which is reliable in operation.
In switches of the type here contemplated, the long term maintenance of desired dimensional relationships of different switch parts and components is important, in order that desired switch action characteristics result, such as: good contact wiping action; contact self-cleaning action; controlled and limited lost motion relative travel of two or more switch parts; reliable switch action notwithstanding dimensional tolerance accumulations; collinear relationship of contacts and actuator line of travel; weld breaking action; and nearparallel relationship of two contacts.
In some applications, and especially those applications of motors used to drive pumps such as jet pumps or swimming pool pumps, circuit controlling switches are mounted outboard of one of the motor end frames to facilitate access thereto. In many pump applications, there may be concern regarding moisture, and it is desirable, e.g., in vertical applications, to provide rain shrouds to prevent rain from entering motor ventilation openings.